112 research outputs found

    Applications of trend surface analysis and geologic model building to mineralized districts in Alaska

    Get PDF
    The Mineral Industry Research Laboratory, University of Alaska, has investigated the application of computers and statistics to mineral deposits in Alaska. Existing programs have been adapted and new ones written for the computers available at the University. The methods tested are trend surface analysis and geologic model making. An existing coeffecient of association program was converted to Fortran IV , but was not applied to an Alaskan problem. A trend surface is a mathematically describable surface that most closely approximates a surface representing observed data. In geologic model making, regression analysis is used to determine what geologic features are significant as ore controls. Coefficient of association compares samples to each other on the basis of a variable being present or absent. Trend surfaces were computed for dips and s t r i k e s of geologic features ( v e i n s , f a u l t s , bedrock) for Southeastern Alaska, the Chichagof district , and the Hyder district . Results for the f i r s t two are presented as maps. Trend surfaces and residual maps were prepared for geochemical data from the Slana district, Alaska. A mineral occurrence model was made for a portion of the Craig Quadrangle, and potential values were computed for c e l l s in the area. Appraisals of potential values by five geologists are compared with those of the model. An IBM 1620 multiple regression program is included

    Copper mineral occurrences in the Wrangell Mountains-Prince William Sound area, Alaska

    Get PDF
    On January 9, 1970, the U.S. Bureau of Mines entered into an agreement with the University of Alaska based upon a proposal submitted by the Mineral Industry Research Laboratory. Under the terms of this agreement, the Laboratory undertook to compile information on copper occurrences in eight quadrangles covering what are loosely known as the Copper River, White River, and Prince William Sound copper provinces. If time permitted four other quadrangles would be added, and this has been possible. Information was to be obtained by searching published and unpublished records of the Bureau of Mines, the U.S. Geological Survey, the State Division of Geological Survey, the University of Alaska, and the recording offices

    Mineral resources of southeastern Alaska

    Get PDF
    This report is part of a series by the Mineral Industry Research Laboratory describing the mineral occurrences of Alaska. Thus far reports have been issued on Northern Alaska (No. 16) Seward Peninsula (No. 18) and the Wrangell Mountain - Prince William Sound areas (No. 27). All of these reports contain tabulations of all deposits described in the literature. Report No, 27 also has computer drawn maps showing locations of mineral occurrences and a computer printout of certain data about each property. The magnetic tape which produced this printout was made as part of the project under which the report was written, It is capable of printing several options, as described in M. I.R. L. Report No. 24. The present report, M, I, R. L. Report No. 28, also contains a printout, and is also backed up by a magnetic tape. The location maps contained in the back pocket of this report have already been published in limited edition as M. I .R. L. Report No. 25, because it was desired to disseminate the information contained on them as fast as possible. It i s hoped that reports such as this eventually will be issued for all of Alaska

    Geochemical-geophysical investigations, Fairbanks district

    Get PDF
    Trace element distribution in a subarctic valley in the Cleary Hill area of the Fairbanks gold district has been studied. Zinc and arsenic have been found excellent pathfinder elements for auriferous deposits. Methods of analysis for copper, lead, zinc, molybdenum, silver and arsenic as well as heavy metals are discussed. The University of Alaska method #2 has been improved, Terrain, slope, and frozen ground have little effect upon the distribution of trace elements associated with the Cleary H i l l vein. A new method for the determination of zinc using dilute acid is proposed. Analysis of geochemical data by trend surface procedures proved effective for localization of anomalies

    Magnetocaloric effect in nano- and polycrystalline manganite La0.7Ca0.3MnO3La_{0.7}Ca_{0.3}MnO_3

    Full text link
    La0.7Ca0.3MnO3La_{0.7}Ca_{0.3}MnO_3 samples were prepared in nano- and polycrystalline forms by sol-gel and solid state reaction methods, respectively, and structurally characterized by synchrotron X-ray diffraction. The magnetic properties determined by ac susceptibility and dc magnetization measurements are discussed. The magnetocaloric effect in this nanocrystalline manganite is spread over a broader temperature interval than in the polycrystalline case. The relative cooling power of the poly- and nanocrystalline manganites is used to evaluate a possible application for magnetic cooling below room temperature.Comment: 6 pages, 5 (double) figures, 1 table, 16 references; submitted to Appl. Phys.

    Grain Surface Models and Data for Astrochemistry

    Get PDF
    AbstractThe cross-disciplinary field of astrochemistry exists to understand the formation, destruction, and survival of molecules in astrophysical environments. Molecules in space are synthesized via a large variety of gas-phase reactions, and reactions on dust-grain surfaces, where the surface acts as a catalyst. A broad consensus has been reached in the astrochemistry community on how to suitably treat gas-phase processes in models, and also on how to present the necessary reaction data in databases; however, no such consensus has yet been reached for grain-surface processes. A team of ∼25 experts covering observational, laboratory and theoretical (astro)chemistry met in summer of 2014 at the Lorentz Center in Leiden with the aim to provide solutions for this problem and to review the current state-of-the-art of grain surface models, both in terms of technical implementation into models as well as the most up-to-date information available from experiments and chemical computations. This review builds on the results of this workshop and gives an outlook for future directions

    Use of SMS texts for facilitating access to online alcohol interventions: a feasibility study

    Get PDF
    A41 Use of SMS texts for facilitating access to online alcohol interventions: a feasibility study In: Addiction Science & Clinical Practice 2017, 12(Suppl 1): A4

    Altered white matter microstructural organization in posttraumatic stress disorder across 3047 adults: results from the PGC-ENIGMA PTSD consortium

    Get PDF
    A growing number of studies have examined alterations in white matter organization in people with posttraumatic stress disorder (PTSD) using diffusion MRI (dMRI), but the results have been mixed which may be partially due to relatively small sample sizes among studies. Altered structural connectivity may be both a neurobiological vulnerability for, and a result of, PTSD. In an effort to find reliable effects, we present a multi-cohort analysis of dMRI metrics across 3047 individuals from 28 cohorts currently participating in the PGC-ENIGMA PTSD working group (a joint partnership between the Psychiatric Genomics Consortium and the Enhancing NeuroImaging Genetics through Meta-Analysis consortium). Comparing regional white matter metrics across the full brain in 1426 individuals with PTSD and 1621 controls (2174 males/873 females) between ages 18-83, 92% of whom were trauma-exposed, we report associations between PTSD and disrupted white matter organization measured by lower fractional anisotropy (FA) in the tapetum region of the corpus callosum (Cohen's d = -0.11, p = 0.0055). The tapetum connects the left and right hippocampus, for which structure and function have been consistently implicated in PTSD. Results were consistent even after accounting for the effects of multiple potentially confounding variables: childhood trauma exposure, comorbid depression, history of traumatic brain injury, current alcohol abuse or dependence, and current use of psychotropic medications. Our results show that PTSD may be associated with alterations in the broader hippocampal network.New methods for child psychiatric diagnosis and treatment outcome evaluatio

    Final report - mineral resources of northern Alaska

    No full text
    Includes 4 plates of maps and other oversized sheets.PURPOSE. This is the final report on the work authorized on July 29, 1967, by the NORTH Commission. The purpose is to inventory mineral resources in northern Alaska and to delineate favorable mineral areas, insofar as possible. Later, a mineral policy study was added and a survey of available airborne geophysics. The Alaska Railroad made possible the large scale dredging at Fairbanks and became a feeder to all interior districts. It allowed the building of military bases during and after World War II. Freight moves predominantly north.Submitted to the NORTH Commission by Mineral Industry Research Laboratory, University of Alask

    Preliminary report mineral resources of northern Alaska

    No full text
    Submitted to the "North Commission"This report is a preliminary report by the Mineral Industry Research Laboratory to the NORTH committee on the subject of mineral resources in the region to be traversed by a proposed railroad
    corecore